Friday, March 12, 2010

carrier rejection


As an important part of near range defense system, near range target detection radar demands effective detection and accurate measurement of target in modern battle field environment. Wideband pseudo code technique with the characteristic of accurate range measurement and good anti-jamming capability is ideal for near range target detection.In this paper, the key technique of modulation and demodulation of wideband BPSK signal in wideband pseudo-random code detection system is discussed. The major work of the dissertation contains several points shown below:Characteristic of pseudo-random code is introduced. High speed m-sequence generator is designed by using the software named ISE8.1 and Xilinx's Viterx-II Pro FPGA chip and simulated in the software ModelSim.The modulation principle of wideband BPSK signal is introduced and the spectrum of BPSK modulated signal is deduced. The modulation circuit of BPSK signal is designed based on broadband quadrature modulator ADL5375. The carrier rejection of the modulation circuit is tested.The demodulation principle of wideband BPSK signal is introduced and the anti-noise performance of coherent demodulation system is discussed. The demodulation circuit of BPSK signal is designed based on broadband quadrature demodulator ADL5382. The amplitude and phase unbalance of the demodulation circuit is tested.

Wednesday, March 3, 2010

Reasons of Juvenile Delinquents

On the one hand, education, I think, shouldn't be reluctant to burden the responsibility of these northface outlet. Currently, when most people think of the word "education", they think of a pupil as a sort of animate sausage casing. Into this empty casing, the north face outlet are supposed to stuff "education". In this way, students were so stuffed with miscellaneous facts, with an indigestible mass of material, that they had no time to draw on their own resources, to use their own minds for analyzing and synthesizing, and evaluating this material. It is imaginable that how it would be when children find they have to confront the teachers with an ax to grind everyday. This way of cheap northface jackets is undoubtedly tedious and futile. Genuine education, as Socrates knew more than two thousand years ago, is not inserting the suffings of information into a person, but rather eliciting knowledge from him, it is drawing out of what is in the mind. Only this way can steer the children toward a glorious future, instead of wandering in the dark corners of streets and bearing endless tediousness of unscrupulous lectures.